Ask SAIL: Topping Off With Solar - Sail Magazine

Ask SAIL: Topping Off With Solar

I was reading “Seeing the Light” (May 2014) about solar power on a budget, and it got me thinking about a similar problem I’ll be facing soon. This summer I will be moving my boat to a dock where there is no shore power for my battery charger.
Author:
Publish date:

Q:Frank Lanza, Kema, TX

I was reading “Seeing the Light” (May 2014) about solar power on a budget, and it got me thinking about a similar problem I’ll be facing soon. This summer I will be moving my boat to a dock where there is no shore power for my battery charger. I have moved it there before for a season and suffice it to say my batteries didn’t survive. I had to replace them. I don’t need anything anywhere near as advanced as the one mentioned in your last issue. All I want to do is put a 2.5- to 5-watt panel on my batteries just to keep them maintained. Would this do the job? And if so would I still need a regulator hooked into them to keep them from overcharging? I have read that on such a low wattage, that it is not necessary.

Nigel Calder is an author and expert on boat systems and diesel engines

Nigel Calder is an author and expert on boat systems and diesel engines

Nigel Calder Replies

Without knowing the of the battery bank, I can only say that the rule of thumb I use is that a panel output of around 3.6 watts is needed for every 100AH of battery capacity being floated. If the solar panel output is much higher than this, you will also need a regulator. But if not, you can get away without a one. Note that the 3.6 watts presupposes there are no loads whatsoever on the battery. If you have even one or two LEDs, like those that are often present in bilge pumps and other circuits, these are likely to drop the charge rate below an effective float charge.

Do you have a question for our experts? Submit it to sailmail@sailmagazine.com

Related

Outremer45

Boat Review: Outremer 45

It’s funny the way things that work right almost inevitably tend to look right as well. Case in point: the Outremer 45, a catamaran that can’t help but turn heads with its large rig, nicely sculpted cabintrunk and narrow, purposeful bows. Better yet, under sail the boat more than ...read more

Sunset-Tyrrel-Bay

Charter: Glorious Grenada

In the wake of the hurricanes that devastated the Virgin Islands last year many charterers ended up going farther south to Grenada and the Grenadines where they found the sailing excellent and the vibe just fine“God must have been a sailor when he created the Caribbean,” a friend ...read more

WaterLinesNov

Waterlines: Tangled Up in Pots

I learned to sail on the Maine coast as a boy, and one of the things my elders taught me was to respect fishing gear. If you got caught up with a lobster pot, you did everything you could to get clear without cutting the pot warp. It represented a family’s livelihood and thus was ...read more

7353

Harken’s Reflex 3 top-down Furler

Furl PowerAre you afraid of flying—spinnakers, that is? Harken’s new Reflex 3 top-down furler will tame A-sails on monohulls from 44-58ft and multis from 39-55ft, and Code 0’s on 39-54ft monos and 36-50ft multis. All you do is heave on the furling line and the sail will roll up ...read more

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell.Got a tip? Send it to sailmail@sailmagazine.comDitch the stress Owners of high-freeboard yachts best boarded via the stern sugar-scoop like to back them into a slip, but the process can be fraught on a windy day or when there’s a current running, ...read more

Sun-Odyssey-490-Bertrand_DUQUENNE-aft

Boat Review: Jeanneau Sun Odyssey 490

True innovation in monohull sailboat design can be a bit elusive these days. That’s not to say that there are no more new ideas, but it does seem that many new tweaks and introductions are a bit incremental: let’s say evolutionary rather than revolutionary. Just when it seems ...read more